Polishing bodies of vegetable fibrous material, in particular polishing wheels, grindstones and sliding contact discs



July 19, 1960 E. GAREIS 2,945,750 OLISHING BODIES OF VEGETABLE FIBROUS MATERIAL, IN

PARTICULAR omsnmc WHEELS, GRINDSTONES AND sums CONTACT DISCS Filed July 12, 1957 INVENTOR.

Bygjgf POLISHING BODIES OF VEGETABLE FIBROUS MA- TERIALJN PARTICULAR POLISHING WHEELS, GRINDSTONES AND SLIDING CONTACT DISCS Erich Gareis, Malmo, Sweden, assignor, by mesne assignments, to Firma bi-flex Birkenstock K.G., Wuppertal, Germany, a corporation of Germany Filed July 12, 1957, Ser. No. 671,529 2 Claims. c1. 51-295 The present invention relates to polishing bodies made of vegetable fibrous material, and in particular to polishing wheels, grindstones and sliding contact discs.

The known conventional polishing wheels, polishing discs, polishing rings and the like are manufactured of woven materials which are 'cut as circular plates oras rmgs. a

It is conventional to use woven material for the manufacture of grinding or polishing discs, which woven material has been used previously for a different purpose and constitutes waste material or which has been at least made for a difierent purpose, so that for instance waste material of new textiles has been used. This woven material does not respond due to its particular structure to the requirements for grinding or polishing discs and not only high wear but also an uneven polishing effect has been experienced with discs made of such material.

It has been proposed before to use preferably woven material made of raw cotton for such polishing discs and rings and to use also such material which is woven of .raw cotton yarn and upon removal from the loom is not subjected to any wet treatment or improvement. Polishing bodies of this type have a permanent quality, yet disclose a comparatively low resistance against wear. polishing effect of fast rotating discs made of such material is further diminished because, due to the effect of the centrifugal force and of other mechanical forces, in-

The

nite States Patent C) dividual threads or thread pieces are removed from the woven material, thereby, causing an unsatisfactory run and an unequal effect on the goods to be polished.

It is, therefore, one object of the present invention to provide polishing bodies which avoid the drawbacks of the known conventional polishing bodies and which provide a very high resistance against wear of the textile goods used for the manufacture of polishing bodies, polishing-grinding and sliding cont-act discs, which textile goods are made of vegetable fibrous material, which also brings about an appreciably improved polishing quality and a better reception of the polishing paste and finally of better reception of the paste on the surfaces of the fibers.

It is another object of the present invention to provide polishing bodies which are made of improved textile material which have been subjected to a treatment of the native fibers changing their physical characteristics.

Generally, the method of preparing polishing bodies according to this invention from vegetable fibers comprises pretreating webs of such fibers with a hot u-amylase solution and, after an intermediate rinse, treating these webs with a sodium hydroxide solution of high concentration and rinsing them again. This alkali treatment at high concentration causes a structural change of the fiber and, thus, of the woven material, consisting in an irreversible swelling of the micellar interstices of the fiber which produces a shrinking in the longitudinal direction of the fiber and a transversal expansion thereof. Inasmuch as the finished woven material is treated rather than the individual fibers making up this material, the

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result is a packing effect upon the web. The warp threads and the weft threads approach each other more closely and twist themselves around each more intimately at their cross points.

The pretreatment with lat-amylase enhances the result of the subsequent alkali treatment, since the effect of the former wrests the cellulose fibers apart from each other for better action of the alkali solution.

I have found that the change in the woven material caused by the physical alterations of the fibers by means of the aforestated treatment results on the one hand in an increase in strength and rigidity of the material and, on the other hand, in a substantial improvement in the polishing action which renders material treated in this manner particularly suitable for use in polishing, grinding and sliding contact discs.

In order to further improve the abrasion resistance of textile polishing structures treated in this manner, and to increase the adhesion of fatty polishing pastes thereto, according to this invention silica is additionally embedded in the textile material.

It is yet still another object of the present invention to provide polishing bodies made of a textile material wherein the individual textile layers forming together the polishing body are punctured with solutions of artificial material or with dispersions of artificial material then superimposed until the thickness of the disc is achieved and then pressed together, so that always the peripheral faces of the fibers on the cylindrical circumference of the polishing discs or the like are effective.

With these and other objects in view which will become apparent in the following detailed description, the present invention will be clearly understood in connection with the accompanying drawing, in which:

Figure 1 is a perspective front view of a polishing discmounted for operation;

Fig. 2 is a perspective front view of a disc showing the compressed disc layers;

Fig. 3 is a schematic showing of the puncturing of the material; and

Fig. 4 is a schematic showing at enlarged scale of thc formation of the puncture points.

The polishing bodies are made in accordance with the present invention in the following manner:

At first a woven material made of raw cotton is sub jected to a washing bath at a temperature of C. with 2 gr. starch reducing rat-amylase per liter, which is obtained from cultures of Bacillus subtilis, having a pH value of 6.5 and a bath relation of 1 to 3. The duration of such treatment is about 2 hours with slow circulation and constant temperature. Upon termination of this treatment the material is washed out at a temperature of 55 C. and then rinsed cold twice.

The treated material is then inserted into an aqueous sodium hydroxide solution of 35 to 50 B. at a temperature ranging from 15 to 50 C. This treatment is terminated when the textile material assumes a glass-like appearance and is performed for a duration of about 10 minutes. Thereafter the material is taken through a hot water bath of about C. for a time period of about 1 minute and then rinsed at first warm at a temperature of 50 C. and fiinally rinsed twice cold until the neutral point is reached.

Thereafter the material is pulled through a 50% dispersion of silica at a temperature of about 20 C., squeezed and then dried tensionless on a cylindrical drying machine.

The textile material treated as set forth above is then cut to form circular blades 1 to form in superposed position a disc (Fig. 1) or the individual layers of a polishing ring which have a greater central opening 2 are superimposed as shown in Fig. 2, after they have been touched up by means of a stamp-like device at points 3 spaced more or less apart from each other with a glue material, preferably a solution of polyvinyl acetate, as shown in Fig. 4. If the desired thickness of the discis reached the entire assembly is subjected to pressure. In this manner a solid connection between the layers is brought about.

The very small points of glue material 3 are irregularly disposed in the respective disc layers, as shown in Fig. 3. They form a solid connecting point between the respective layer 1 similar to the showing inFig. 4.

By arranging a structure in accordance with the present invention a polishing or grinding disc body is achieved, the layers of 'which do not open and do not give during the working due to the engaging pressure of the workpiece. The disc .shows very little Wear and has a very high polishing power.

While I have disclosed one embodiment of the present invention, it is to be understood that this embodiment is given by example only and not in a limiting sense, the scope of the present invention being determined by the objects and the claims.

I claim:

1. A method of treating woven material consisting of vegetable fibers for making polishing, grinding and sliding contact discs, comprising treating the woven material first for about two hours at 75 C. with a 0.2 percent a-amylase solution having a pH of 6.5, washing with hot water of a temperature of about 55 C. and then with cold water, treating the material for about ten minutes at a temperature ranging from 15 C. to 50 C. with anaqueous. sodium hydroxide solution of to B., washing with hot water of a temperature of about C. and then with cold water until neutral, and drying.

2. The method as set forth in claim 1, wherein said sodium hydroxide treated and washed material is treated with a dispersion of silica.

References Cited in the file of this patent UNITED STATES PATENTS 2,166,570 Panissidi July 18, 1939 2,355,667 Melton et a1 Aug. 15, 1944 2,375,263 Upper May 8, 1945 2,609,284 Nestor Sept. 2, 1952 2,747,981 Brown et a1 May 29, 1956 OTHER REFERENCES Mercerising by Marsh, pages 99, and 437 (1942). 

1. A METHOD OF TREATING WOVEN MATERIAL CONSISTING OF VEGETABLE FIBERS FOR MAKING POLISHING, GRINDING AND SLIDING CONTACT DISCS, COMPRISING TREATING THE WOVEN MATERIAL FIRST FOR ABOUT TWO HOURS AT 75*C. WITH A 0.2 PERCENT A-AMYLASE SOLUTION HAVING A PH OF 6.5, WASHING WITH HOT WATER OF A TEMPERATURE OF ABOUT 55*C. AND THEN WITH COLD WATER, TREATING THE MATERIAL FOR ABOUT TEN MINUTES AT A TEMPERATURE RANGING FROM 15*C. TO 50*C. WITH AN AQUEOUS SODIUM HYDROXIDE SOLUTION OF 35* TO 50* BE., WASHING WITH HOT WATER OF A TEMPERATURE OF ABOUT 55*C. AND THEN WITH COLD WATER UNTIL NEUTRAL, AND DRYING.
 2. THE METHOD AS SET FORTH IN CLAIM 1, WHEREIN SAID SODIUM HYDROXIDE TREATED AND WASHED MATERIAL IS TREATED WITH A DISPERSION OF SILICA. 